
    public class BinarySearchTree {
        static class TreeNode {
            public int val;
            public TreeNode left;
            public TreeNode right;

            public TreeNode(int val) {
                this.val = val;
            }
        }

        public TreeNode root = null;

        public boolean search(int val) {
            TreeNode cur = root;
            while (cur != null) {
                if(cur.val < val) {
                    cur = cur.right;
                }else if(cur.val > val) {
                    cur = cur.left;
                }else {
                    return true;
                }
            }
            return false;
        }

        public boolean insert(int val) {
            TreeNode node = new TreeNode(val);
            if(root == null) {
                root = node;
                return true;
            }
            TreeNode cur = root;
            TreeNode parent = null;
            while (cur != null) {
                if(cur.val <val) {
                    parent = cur;
                    cur = cur.right;
                }else if(cur.val > val) {
                    parent = cur;
                    cur = cur.left;
                }else {
                    return false;
                }
            }
            if(parent.val < val) {
                parent.right = node;
            }else {
                parent.left = node;
            }
            return true;
        }

        public void remove(int val) {
            TreeNode cur = root;
            TreeNode parent = null;
            while (cur != null) {
                if(cur.val <val) {
                    parent = cur;
                    cur = cur.right;
                }else if(cur.val > val) {
                    parent = cur;
                    cur = cur.left;
                }else {
                    //删除的逻辑
                    removeNode(parent,cur);
                    return;
                }
            }
        }
        private void removeNode(TreeNode parent,TreeNode cur) {

            if(cur.left == null) {
                if(cur == root) {
                    root = cur.right;
                }else if(cur == parent.left) {
                    parent.left = cur.right;
                }else {
                    parent.right = cur.right;
                }
            }else if(cur.right == null) {
                if(cur == root) {
                    root = cur.left;
                }else if(cur == parent.left) {
                    parent.left = cur.left;
                }else {
                    parent.right = cur.left;
                }
            }else {

                TreeNode targetParent = cur;
                TreeNode target = cur.right;
                while (target.left != null) {
                    targetParent = target;
                    target = target.left;
                }
                cur.val = target.val;

                if(target == targetParent.left) {
                    targetParent.left = target.right;
                }else {
                    targetParent.right = target.right;
                }
            }
        }


    }